Hydraulic excavators and other construction vehicles typically comprise a fuel oil tank for storing fuel oil, and a hydraulic oil tank for storing hydraulic oil. A technique is widely used in which the fuel oil tank and the hydraulic oil tank are integrally coupled to constitute an “oil storage tank,” whereby the rigidity of each of the two tanks is mutually improved.
There are known techniques for providing a breather valve to the upper face of the hydraulic oil tank in order to adjust the amount of air inside the hydraulic oil tank in accordance with the rise and fall of the fluid face the hydraulic oil (e.g., Japanese Laid-open Patent Application Nos. 2006-46016 and 2007-177501). However, with such techniques, gravel and/or dust are liable to penetrate the interior of the hydraulic oil tank via the breather valve. In view of the above, a technique has been proposed for attaching the breather hose to the breather valve and drawing the breather hose along the side face of the hydraulic oil tank (Japanese Laid-open Patent Application No. 2009-30346).